Kinematic Analysis of Dysphagia: Significant Parameters of Aspiration Related to Bolus Viscosity

Swallowing kinematics and submental muscles activation during a newly designed maneuver called Mouth Open Swallowing Maneuver: A comparative study

The aim of this study was to design a new maneuver called the Mouth Open Swallowing Maneuver (MOSM), and to compare swallowing kinematics and submental muscles activation (SMA) between MOSM and two current approaches used in dysphagia rehabilitation. Fifty healthy volunteers were asked to perform three repetitions of dry swallowing (DS) (control task), the MOSM, the Mendelsohn Maneuver (MM), and the Tongue-Hold Maneuver (THM) during videofluoroscopic swallowing study accompanied with simultaneous SMA recording. Swallowing kinematics were measured by frame-by-frame analysis on hyolaryngeal movement using ImageJ. Swallowing with maximum hyolaryngeal movement and SMA during these tasks was used for comparative analysis. Vertical movement of the hyoid during the MOSM was significantly greater than those observed during the DS and the THM (p<0.001, p<0.001). Horizontal movement of the hyoid during DS and the THM was significantly greater than that observed during the MM (p = 0.001, p = 0.001). Vertical movement of the larynx during the MOSM was significantly greater than those observed during DS, MM, and THM (p<0.001). There was no significant difference between tasks in horizontal movement of the larynx (p = 0.785). SMA during the THM was significantly greater than that observed during MOSM (p = 0.002). No significant difference was found between other tasks in terms of SMA (p>0.05). The MOSM as a newly designed maneuver was significantly superior to other maneuvers in increasing vertical hyolaryngeal movement. The THM has as much effect on hyolaryngeal movement as the MM. In this study, the MOSM was shown to be effective in increasing hyolaryngeal movement. ClinicalTrials.gov Protocol Registration and Results System (PRS); the clinical trial registration number (NCT05579041).

Quantifying Oropharyngeal Swallowing Impairment in Response to Bolus Viscosity

PURPOSE

The purpose of this study was to test the feasibility for quantifying changes in oropharyngeal swallowing impairment in response to alteration in bolus viscosity using a reliable and valid method of observational measurement-the Modified Barium Swallow Impairment Profile (MBSImP).

METHOD

This retrospective analysis included a heterogeneous cohort of 119 patients with suspected dysphagia that underwent a videofluoroscopic swallowing study as part of clinical care. Using consensus scoring, two expert clinicians assigned MBSImP scores to components related to oropharyngeal swallowing function between two bolus viscosities (thin liquid and pudding): epiglottic movement, laryngeal elevation, anterior hyoid excursion, tongue base retraction, pharyngeal stripping wave, and pharyngoesophageal segment opening (PESO). Comparisons between the two bolus viscosities were investigated for each component.

RESULTS

Higher (worse) scores were observed in the thin-liquid trial compared with the pudding trial for the following MBSImP components: anterior hyoid excursion (p = .03), epiglottic movement (p < .001), pharyngeal stripping wave (p < .001), and PESO (p = .002). Lower (better) scores were observed in the liquid trial compared with the pudding trial for one component-tongue base retraction (Component 15) only (p < .001).

CONCLUSION

These findings provide further evidence for positive influences of viscosity on the swallow mechanism, including influences of sensory feedback on the sensorimotor swallow program.

Non-Contact Assessment of Swallowing Dysfunction Using Smartphone Captured Skin Displacements

Early and accurate dysphagia diagnosis is essential for reducing the risk of associated co-morbidities and mortalities. Barriers to current evaluation methods may alter the effectiveness of identifying at-risk patients. This preliminary study evaluates the feasibility of using iPhone X-captured videos of swallowing as a non-contact dysphagia screening tool. Video recordings of the anterior and lateral necks were captured simultaneously with videofluoroscopy in dysphagic patients. Videos were analyzed using an image registration algorithm (phase-based Savitzky-Golay gradient correlation (P-SG-GC)) to determine skin displacements over hyolaryngeal regions. Biomechanical swallowing parameters of hyolaryngeal displacement and velocity were also measured. Swallowing safety and efficiency were assessed by the Penetration Aspiration Scale (PAS), Residue Severity Ratings (RSR), and the Normalized Residue Ratio Scale (NRRS). Anterior hyoid excursion and horizontal skin displacements were strongly correlated with swallows of a 20 mL bolus (r_s = 0.67). Skin displacements of the neck were moderately to very strongly correlated with scores on the PAS (r_s = 0.80), NRRS (r_s = 0.41-0.62), and RSR (r_s = 0.33). This is the first study to utilize smartphone technology and image registration methods to produce skin displacements indicating post-swallow residual and penetration-aspiration. Enhancing screening methods provides a greater chance of detecting dysphagia, reducing the risk of negative health impacts.

Rheological Issues on Oropharyngeal Dysphagia

There is an increasing proof of the relevance of rheology on the design of fluids for the diagnosis and management of dysphagia. In this sense, different authors have reported clinical evidence that support the conclusion that an increase in bolus viscosity reduces the risks of airway penetration during swallowing. However, this clinical evidence has not been associated yet to the definition of objective viscosity levels that may help to predict a safe swallowing process. In addition, more recent reports highlight the potential contribution of bolus extensional viscosity, as elongational flows also develops during the swallowing process. Based on this background, the aim of this review paper is to introduce the lecturer (experts in Dysphagia) into the relevance of Rheology for the diagnosis and management of oropharyngeal dysphagia (OD). In this sense, this paper starts with the definition of some basic concepts on Rheology, complemented by a more extended vision on the concepts of shear viscosity and elongational viscosity. This is followed by a short overview of shear and elongational rheometrical techniques relevant for the characterization of dysphagia-oriented fluids, and, finally, an in-depth analysis of the current knowledge concerning the role of shear and elongational viscosities in the diagnosis and management of OD (shear and elongational behaviors of different categories of dysphagia-oriented products and contrast fluids for dysphagia assessment, as well as the relevance of saliva influence on bolus rheological behavior during the swallowing process).

Temporal Sequence of Laryngeal Vestibule Closure and Reopening is Associated With Airway Protection

BACKGROUND

Upper esophageal sphincter opening (UESO), and laryngeal vestibule closure (LVC) are two essential kinematic events whose timings are crucial for adequate bolus clearance and airway protection during swallowing. Their temporal characteristics can be quantified through time-consuming analysis of videofluoroscopic swallow studies (VFSS).

OBJECTIVES

We sought to establish a model to predict the odds of penetration or aspiration during swallowing based on 15 temporal factors of UES and laryngeal vestibule kinematics.

METHODS

Manual temporal measurements and ratings of penetration and aspiration were conducted on a videofluoroscopic dataset of 408 swallows from 99 patients. A generalized estimating equation model was deployed to analyze association between individual factors and the risk of penetration or aspiration.

RESULTS

The results indicated that the latencies of laryngeal vestibular events and the time lapse between UESO onset and LVC were highly related to penetration or aspiration. The predictive model incorporating patient demographics and bolus presentation showed that delayed LVC by 0.1 s or delayed LVO by 1% of the swallow duration (average 0.018 s) was associated with a 17.19% and 2.68% increase in odds of airway invasion, respectively.

CONCLUSION

This predictive model provides insight into kinematic factors that underscore the interaction between the intricate timing of laryngeal kinematics and airway protection. Recent investigation in automatic noninvasive or videofluoroscopic detection of laryngeal kinematics would provide clinicians access to objective measurements not commonly quantified in VFSS. Consequently, the temporal and sequential understanding of these kinematics may interpret such measurements to an estimation of the risk of aspiration or penetration which would give rise to rapid computer-assisted dysphagia diagnosis.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:521-527, 2023.

Compensatory Effects of Sequential 4-Channel Neuromuscular Electrical Stimulation for the Treatment of Acute, Subacute, and Chronic Dysphagia in a Prospective, Double-Blinded Randomized Clinical Trial

Background. The precise mechanism of 2-channel neuromuscular electrical stimulation (NMES) treatment is unknown, and controversy remains over its efficacy. The sequential 4-channel NMES was newly developed based on normal contractile sequences of swallowing-related muscles. Objective. To assess the clinical efficacy of sequential 4-channel NMES during swallowing. Methods. In this prospective RCT, 52 inpatients with dysphagia (acute, subacute, and chronic state) after stroke, brain tumor, or encephalitis were enrolled. Participants who underwent a videofluoroscopic swallowing study (VFSS) and clinical evaluation were enrolled and were randomly assigned to the 4-channel NMES or sham group. The 4-channel NMES and sham groups swallowed thin and honey-like fluids under NMES (sequential stimulation on suprahyoid and infrahyoid) and sham stimulation, respectively. The procedures were evaluated with the VFSS. Pre- and post-treatment evaluations were performed with the videofluoroscopic dysphagia scale (VDS), penetration-aspiration scale (PAS), Likert scale, and kinematic analysis. Results. The 4-channel NMES group showed significantly greater improvements than the sham group with respect to oral VDS, pharyngeal VDS, total VDS, and PAS (P < .05). Furthermore, the Likert scale for satisfaction, easiness, and discomfort for swallowing showed favorable results for the 4-channel NMES group (P < .05). In the kinematic analysis, the peak speed point, distance, and velocity of hyoid movement were significantly greater in the 4-channel NMES group (P < .05). Conclusions. Sequential 4-channel NMES activating the suprahyoid, thyrohyoid, and other infrahyoid muscles during swallowing showed significant clinical improvement with respect to VDS, PAS, and kinematic analysis. Therefore, sequential 4-channel NMES is a potential new functional electrical stimulation system for the treatment of dysphagia.

Treatment burden associated with the intake of thickened fluids

The implementation of thickened fluids in patients with dysphagia is widely considered an effective strategy for safe and physiologically improved swallow. However, there is limited evidence to suggest that this intervention reduces the risk of dysphagia-related complications including aspiration pneumonia. In addition, there is growing evidence that this approach is associated with adverse clinical effects including dehydration, malnutrition and reduced health-related quality of life. This review summarises the rationale for thickened fluids, the evidence base (or lack thereof) underpinning their use, and current guideline recommendations.

Educational aims

To review the evidence base for thickened fluids in the management of dysphagia.To examine the evidence that thickened fluids reduce aspiration pneumonia.To provide an overview of the advantages and disadvantages of thickened fluids in the management of dysphagia.

Clinical effectiveness of the sequential 4-channel NMES compared with that of the conventional 2-channel NMES for the treatment of dysphagia in a prospective double-blind randomized controlled study

Background

To date, conventional swallowing therapies and 2-channel neuromuscular electrical stimulation (NMES) are standard treatments for dysphagia. The precise mechanism of 2-channel NMES treatment has not been determined, and there are controversies regarding the efficacy of this therapy. The sequential 4-channel NMES was recently developed and its action is based on the normal contractile sequence of swallowing-related muscles.

Objective

To evaluate and compare the rehabilitative effectiveness of the sequential 4-channel NMES with that of conventional 2-channel NMES.

Methods

In this prospective randomized case–control study, 26 subjects with dysphagia were enrolled. All participants received 2- or 4-channel NMES for 2–3 weeks (minimal session: 7 times, treatment duration: 300–800 min). Twelve subjects in the 4-channel NMES group and eleven subjects in the 2-channel NMES group completed the intervention. Initial and follow-up evaluations were performed using the videofluoroscopic dysphagia scale (VDS), the penetration-aspiration scale (PAS), the MD Anderson dysphagia inventory (MDADI), the functional oral intake scale (FOIS), and the Likert scale.

Results

The sequential 4-channel NMES group experienced significant improvement in their VDS (oral, pharyngeal, and total), PAS, FOIS, and MDADI (emotional, functional, and physical subsets) scores, based on their pretreatment data. VDS (oral, pharyngeal, and total) and MDADI (emotional and physical subsets) scores, but not PAS and FOIS scores, significantly improved in the 2-channel NMES group posttreatment. When the two groups were directly compared, the 4-channel NMES group showed significant improvement in oral and total VDS scores.

Conclusions

The sequential 4-channel NMES, through its activation of the suprahyoid and thyrohyoid muscles, and other infrahyoid muscles mimicking physiological activation, may be a new effective treatment for dysphagia.

Trial registration: clinicaltrial.gov, registration number: NCT03670498, registered 13 September 2018, https://clinicaltrials.gov/ct2/show/NCT03670498?term=NCT03670498&draw=2&rank=1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00884-6.

Increased viscosity of milk during infant feeding improves swallow safety through modifying sucking in an animal model

Infants experiencing frequent aspiration, the entry of milk into the airway, are often prescribed thickened fluids to improve swallow safety. However, research on the outcomes of thickened milk on infant feeding have been limited to documenting rates of aspiration and the rheologic properties of milk following thickening. As a result, we have little insight into the physiologic and behavioral mechanisms driving differences in performance during feeding on high viscosity milk. Understanding the physiologic and behavioral mechanisms driving variation in performance at different viscosities is especially critical, because the structures involved in feeding respond differently to sensory stimulation. We used infant pigs, a validated animal model for infant feeding, to test how the tongue, soft palate, and hyoid respond to changes in viscosity during sucking and swallowing, in addition to measuring swallow safety and bolus size. We found that the tongue exhibited substantive changes in its movements associated with thickened fluids during sucking and swallowing, but that pharyngeal transit time as well as hyoid and soft palate movements during swallowing were unaffected. This work demonstrates the integrated nature of infant feeding and that behaviors associated with sucking are more sensitive to sensorimotor feedback associated with changes in milk viscosity than those associated with the pharyngeal swallow, likely due to its reflexive nature.

Predicting penetration-aspiration through quantitative swallow measures of children: a videofluoroscopic study

PURPOSE

Quantitative measures have improved the reliability and accuracy in interpretation and reporting of videofluoroscopy (VFSS). Associations between quantitative VFSS measures and swallow safety in children are not widely reported. The ability to predict aspiration in children, even if not observed during brief VFSS, will improve diagnostic reporting and potentially reduce the need for extended radiation time. The aims of this study were to determine associations between quantitative fluoroscopic swallow measures and penetration-aspiration and to predict likelihood of penetration-aspiration.

METHODS

We selected videofluoroscopic data of 553 children from a pediatric hospital database for this single-center retrospective observational study. A standard protocol of VFSS administration was used and data were recorded at 30 frames-per-second. A set of quantitative and descriptive swallow measures was obtained using a specialized software with satisfactory inter-rater and intra-rater reliability. Binomial logistic regression with backward likelihood ratio was conducted, while controlling for age, gender, and etiology.

RESULTS

We found bolus clearance ratio (BCR), pharyngeal constriction ratio (PCR), duration to hyoid maximal elevation (Hdur), and total pharyngeal transit time (TPT) to be predictive of penetration-aspiration in children. PCR was the most predictive of penetration-aspiration in children (61.5%). Risk of aspiration was more than 100 times, when BCR =  ≥ 0.1, TPT =  ≥ 2 s, Hdur =  > 1 s or PCR =  ≥ 0.2 (p < 0.05 for all measures).

CONCLUSION

The results confirm the potential of objective quantitative swallow measures in predicting the risk of aspiration in children with dysphagia. These parameters provide predictive measures of aspiration risk that are clinically useful in identifying children of concern, even if no aspiration is observed during VFSS.

Epiglottic Retroflexion is a Key Indicator of Functional Recovery of Post-stroke Dysphagia

Objective

To evaluate the longitudinal changes of swallowing kinematics based on videofluoroscopic swallowing studies (VFSSs) in subacute stroke patients grouped according to the method of dietary intake.

Methods

Sixty-nine subacute stroke patients who had taken at least 2 successive VFSSs were included. Subjects were allocated into 3 groups according to the degree of swallowing function recovery—not improved group (tube feeding recommended to patients at both studies), improved group (tube feedings recommended initially to patients and oral feeding recommended at follow-up study), and well-maintained group (oral feeding at both studies recommended to patients). Initial VFSS was performed during the subacute stage of stroke, 1 to 12 weeks after the onset of stroke, and follow-up VFSS was performed at least once. Kinematic variables were calculated by two-dimensional motion analysis of multiple structures, including the hyoid bone, epiglottis, and vocal cord. Changes of kinematic variables were analyzed in serial VFSSs.

Results

At the initial VFSS, the well-maintained group showed significantly larger angles of epiglottic folding than the not improved group, while at the follow-up VFSS, the improved and the well-maintained groups showed significantly larger epiglottic folding angles than the not improved group. The distribution of epiglottic folding angles was in a dichotomous pattern, and each cluster was related to the swallowing function.

Conclusion

This study showed that improved epiglottic folding angles are associated with the recovery of the swallowing process and suitability for oral feeding among various kinematic variables in subacute stroke patients.

Twenty years of quantitative instrumental measures of swallowing in children: a systematic review

Early identification and intervention has shown better health outcomes for children with dysphagia. Instrumental swallowing assessments are vital and have been a focus of dysphagia research in the last two decades. This systematic review explores published quantitative instrumental measures of swallowing in children. Five subject-related databases were searched to identify original scientific articles published in English, using instrumental quantitative measures of swallowing to study swallowing/feeding mechanism in children since 1998. Two thousand two hundred and two articles were found from the initial database search and 36 were included in the final qualitative synthesis following PRISMA guidelines. Selected studies showed great diversity in target population, phase/s of swallowing studied, instrumentation used (n = 10) and quantitative measures reported (n = 144). Videofluoroscopy and manometry have been studied most repeatedly. With less frequency, a variety of other instruments has been used to describe suck-swallow patterns and swallowing-related respiration. High-resolution manometry shows the greatest increase in publications with validated, reliable quantitative measures of pharyngeal and oesophageal pressures and timing. More recently, quantification of videofluoroscopy analysis has been a focus.Conclusion: A diverse range of quantitative measures of swallowing is available for children in the literature. However, further reliability and validity testing is needed. Opportunities for clinical application of these quantitative manometric and videofluoroscopic measures are restricted by limited normative comparisons and vast variability in published measures.What is known?• Instrumental swallowing assessments are reliable and accurate in diagnosing swallowing difficulties in children.• However, subjective interpretation of observational findings often questions the optimal use of instrumentation.What is new?• High-resolution manometry has shown promising progress with the development of quantitative objective swallow measures for children. While attempts to quantify video-fluoroscopic measures have been increased in the recent past.• A vast variety of instruments has been used to obtain quantitative and/or objective swallow measures of children, yet clinical application is still in progress.

Consistencies and terminologies - the use of the International Dysphagia Diet Standardization Initiative

Introduction

Introduction: this study aimed to verify the ability of speech therapists to identify, sort and name the different consistencies used in neurogenic oropharyngeal dysphagia (NOD) management, and to compare the results with the terms proposed by the International Dysphagia Diet Standardization Initiative (IDDSI). Methods: this research was approved by the ethics committee. Sixty speech therapists who work with NOD patients sorted 5 commercial foods from thinnest to thickest to match IDDSI levels 0 to 4, and then used a term to designate each consistency. Results: most subjects (76.66%) sorted the foods properly. Terminologies were divergent at all levels. For level 0, practitioners assigned 3 different terms. For level 1, 24 different terms were reported; for level 2 there were 25 terms, 23 terms for level 3, and 18 terms for level 4. Level 0 (IDDSI - thin) was designated by most participants as liquid; level 1 (IDDSI - slightly thick) was referred to as semi-thickened liquid; level 2 (IDDSI - mildly thick) as thickened liquid; level 3 (IDDSI - moderately thick) as honey; and level 4 (IDDSI - extremely thick) as pasty by most subjects. A reduced number of participants used terms in accordance with IDDSI. Level 0 was appropriately named by 5 subjects (8.33%); levels 1, 2 and 4 by 2 practitioners each (3.33%); and level 3 by 1 professional (1.66%). None of the subjects named all 5 IDDSI levels correctly. Conclusion: most practitioners progressed consistencies properly. There was a diversity of terminologies used for the same consistency at all levels, with no standardization.

Application of Automatic Kinematic Analysis Program for the Evaluation of Dysphagia in ALS patients

Dysphagia in amyotrophic lateral sclerosis (ALS) increases the risk of malnutrition, dehydration, and aspiration pneumonia. Kinematic analysis of videofluoroscopic swallowing study (VFSS) can provide detailed movement of the hyoid bone, revealing abnormalities of swallowing in ALS patients. We developed an automated kinematic analysis program (AKAP) that analyzes the trajectory of the hyoid bone via a visual tracking method. The aim of this study was to investigate the hyoid movement in ALS patients using AKAP and compare it with non-dysphagic subjects. Thirty ALS patients who underwent VFSS in Seoul National University Bundang Hospital between 2015 and 2017 were recruited. For comparison, 30 age-matched control subjects were also enrolled; the same swallowing study was conducted using thin fluid and yogurt. The hyoid bone movement was analyzed by evaluating the vertical and horizontal distances with four peak points (A, B, C, D), and the time of each point were also calculated. With respect to distance parameters, only vertical peak distance (distance between B, D points) during thin fluid swallowing was significantly decreased in ALS patients. (p = 0.038) With respect to temporal parameters, Time ABC, Time ABCD, and Duration C were significantly increased in ALS patients when swallowing both thin fluid and yogurt. (Time ABC p = 0.019, p = 0.002; Time ABCD p = 0.001, p = 0.004; Duration C p = 0.004, p = 0.025 respectively). This result revealed that dysphagia in ALS patient is caused by decreased velocity of hyoid bone movement due to the development of weakness in swallowing-related muscles. The parameters of kinematic analysis could be used to quantitatively evaluate dysphagia in motor neuron disease.

Feasibility of high-resolution manometry for decision of feeding methods in patients with amyotrophic lateral sclerosis

As amyotrophic lateral sclerosis (ALS) progresses, dysphagia gets worse due to the weakening of pharyngeal musculature. As oral feeding becomes more difficult or dangerous due to worsening dysphagia, tracheal aspiration, or undernutrition, the necessity for tube feeding becomes increasingly important. This study aims to establish a standard pressure point by applying pharyngeal pressure using high-resolution manometry (HRM) to start tube feeding in patients with ALS.This study was designed as a retrospective analysis of prospectively collected data. Forty-one patients with ALS and 20 healthy subjects were participated. Both groups were evaluated using HRM, videofluoroscopic swallowing study (VFSS), and pulmonary function test. The swallowing pressure along the velopharynx (VP), tongue base (TB), pre-upper esophageal sphincter (UES), lower pharynx, and cricopharyngeus, as well as minimal UES pressure were measured using HRM.There was significantly positive correlation between the pressure of cricopharyngeus and forced expiratory volume in 1 second (FEV1). And there were significant correlations between results of VFSS and FEV1, FEV1%, forced vital capacity (FVC), and FVC%. There was a significant difference in the pressure of TB and cricopharyngeus between the control group and the ALS patient group. The pressures of VP, TB, lower pharynx, and cricopharyngeus have a significant correlation with the recommended feeding type by VFSS.Because it is possible to use HRM to quantitatively assess pharyngeal and respiratory weaknesses and it is more sensitive than other evaluation tools, the cutoff value of HRM parameters may be used to decide the feeding type in patients with ALS.

Current approaches to instrumental assessment of swallowing in children

PURPOSE OF THE REVIEW

This article reviews recent developments in the instrumental assessment of swallowing in children with a specific focus on research published between January 2017 and June 2018.

RECENT FINDINGS

Instrumental swallowing assessments reported in the time period included: videofluoroscopic study of swallowing, digital cervical auscultation, dynamic ultrasound, high-resolution impedance manometry, nasal airflow thermistry and respiratory inductance plethysmography. Several studies were found exploring tools to objectively quantify videofluoroscopic study of swallowing data; swallowing from the mouth through to stomach was addressed including approaches to analysing mastication as well as evaluating oesophageal motility disorders.

SUMMARY

Even though a vast range of instrumentation were studied, lack of clarity on clinical feasibility and objective measures that facilitate medical decision-making in practice mean further research is required to provide guidance on implementation. Promising novel approaches to aid the quantification of swallowing physiology from the mouth, pharynx and through to the oesophagus are emerging.

Predicting aspiration risk in patients with dysphagia: Evidence from fluoroscopy

Objective

To investigate the potential of timing and displacement measures from fluoroscopic swallow studies for predicting aspiration in dysphagic patients.

Methods

Timing and displacement variables for a 20‐ml liquid bolus were extracted from fluoroscopic swallow studies of 5923 patients reflecting a variety of dysphagia etiologies. Patients were divided into aspirators and non‐aspirators, and variables were compared between groups, and to a group of 148 normal control subjects. The relationship of each variable to aspiration was determined. Odds ratios for aspiration were calculated for measures deviating more than two standard deviations from normal. Associations of variables with time of aspiration relative to airway closure were also examined.

Results

Regression analyses revealed that the pharyngeal constriction ratio (PCR) was the measure most predictive of aspiration (74.6%), with percentage of accuracy improving to 76.5% when all measures were considered. Odds Ratios ranging from two times to more than five times were identified for variables deviating more than two standard deviations from normal. Aspiration relative to maximum airway closure, ie, before, during, and after, was also investigated. In the current study, 53% of aspiration events occurred after maximum airway closure, on residue that remained after swallow. Some mechanical impairments appeared specific to timing of aspiration and provide further evidence of the utility of mechanical analysis.

Conclusions

Results of the review provide substantial support for the value of quantitative assessment of swallow mechanics, and for the role of such data in predicting aspiration risk in dysphagic patients.

Level of Evidence

3b (retrospective, individual case‐control)

Swallowing outcomes in patients with subcortical stroke associated with lesions of the caudate nucleus and insula

Objective The present study was performed to investigate the relationships between swallowing outcomes and lesion location, bolus characteristics, and age in patients with subcortical stroke.

PATIENTS

Patients with subcortical and insular stroke (mean age, 57.38 ± 12.71 years) were investigated. All patients (n = 21) completed both brain magnetic resonance imaging studies and videofluoroscopic swallowing studies. Main Outcome Measures The oral transit duration, pharyngeal transit duration (PTD), laryngeal response duration, and Penetration-Aspiration Scale (PAS) score were applied to examine the efficiency of propulsion and airway protection in three swallowing tasks. Path analyses were performed to assess the relationships between swallowing outcomes and lesion location, age, bolus viscosity, and bolus volume. Results Caudate nucleus (CN) lesions were associated with higher PAS scores. Insular lesions were associated with a longer PTD. Advanced age was associated with a longer PTD. Bolus viscosity significantly moderated the association between CN lesions and higher PAS scores. Conclusions In the present cohort, CN lesions impacted airway protection and insular lesions impacted pharyngeal transit. An increased bolus viscosity reduced the aspiration severity. These results suggest that lesion location is an important indicator to predict subsequent dysphagia in patients with subcortical stroke.

The anatomy and physiology of normal and abnormal swallowing in oropharyngeal dysphagia

BACKGROUND

Eating and drinking are enjoyable activities that positively impact on an individual's quality of life. The ability to swallow food and fluid is integral to the process of eating. Swallowing occupies a dual role being both part of the enjoyment of eating and being a critically important utilitarian activity to enable adequate nutrition and hydration. Any impairment to the process of swallowing can negatively affect a person's perception of their quality of life. The process of swallowing is highly complex and involves muscles in the mouth, pharynx, larynx, and esophagus. The oropharynx is the anatomical region encompassing the oral cavity and the pharynx. Food must be masticated, formed into a bolus and transported to the pharynx by the tongue whereas fluids are usually held within the mouth before being transported ab-orally. The bolus must then be transported through the pharynx to the esophagus without any matter entering the larynx. The muscles needed for all these steps are coordinated by swallowing centers within the brainstem which are supplied with sensory information by afferent nerve fibers from several cranial nerves. The swallowing centers also receive modulatory input from higher centers within the brain. Hence, a swallow has both voluntary and involuntary physiologic components and the term dysphagia is given to difficult swallowing while oropharyngeal dysphagia is difficult swallowing due to pathology within the oropharynx.

PURPOSE

Problems affecting any point along the complex swallowing pathway can result in dysphagia. This review focuses on the anatomy and physiology behind normal and abnormal oropharyngeal swallowing. It also details the common diseases and pathology causing oropharyngeal dysphagia.

Swallowing Mechanics Associated With Artificial Airways, Bolus Properties, and Penetration-Aspiration Status in Trauma Patients

PURPOSE

Artificial airway procedures such as intubation and tracheotomy are common in the treatment of traumatic injuries, and bolus modifications may be implemented to help manage swallowing disorders. This study assessed artificial airway status, bolus properties (volume and viscosity), and the occurrence of laryngeal penetration and/or aspiration in relation to mechanical features of swallowing.

METHOD

Coordinates of anatomical landmarks were extracted at minimum and maximum hyolaryngeal excursion from 228 videofluoroscopic swallowing studies representing 69 traumatically injured U.S. military service members with dysphagia. Morphometric canonical variate and regression analyses examined associations between swallowing mechanics and bolus properties based on artificial airway and penetration-aspiration status.

RESULTS

Significant differences in swallowing mechanics were detected between extubated versus tracheotomized (D = 1.32, p < .0001), extubated versus decannulated (D = 1.74, p < .0001), and decannulated versus tracheotomized (D = 1.24, p < .0001) groups per post hoc discriminant function analysis. Tracheotomy-in-situ and decannulated subgroups exhibited increased head/neck extension and posterior relocation of the larynx. Swallowing mechanics associated with (a) penetration-aspiration status and (b) bolus properties were moderately related for extubated and decannulated subgroups, but not the tracheotomized subgroup, per morphometric regression analysis.

CONCLUSION

Specific differences in swallowing mechanics associated with artificial airway status and certain bolus properties may guide therapeutic intervention in trauma-based dysphagia.

Evaluation of the natural history of patients who aspirate

OBJECTIVES/HYPOTHESIS

The natural clinical progression of aspiration to eventual pulmonary compromise is not well understood. We hypothesized that dietary modification recommendations, Penetration-Aspiration Scale (PAS) score, and dysphagia etiology would be associated with changes in time to first pulmonary event and overall survival for patients with documented aspiration on radiologic testing. This study identified a cohort of patients with detectable unsensed penetration or aspiration on videofluoroscopic swallowing study (VFSS), and followed this cohort over time for development of pulmonary events and death. We then evaluated the association of aspiration severity and dietary modification recommendations on incidence of these endpoints.

STUDY DESIGN

Retrospective chart review.

METHODS

A total of 2,616 VFSS exam reports were reviewed from our institution performed between January 1, 2009 and December 31, 2010. Aspiration or unsensed penetration (PAS of 5 or greater) was detected in 564 (21.5%) of these patients, who were then included in the study cohort. Medical records were reviewed retrospectively for development of pulmonary events (pneumonia, pneumonitis, or other life-threatening pulmonary illness) and all-cause mortality for up to 54 months after initial VFSS. Univariate Kaplan-Meier analysis and multivariate Cox regression were performed for time to first pulmonary event and survival predicted by recommended diet, PAS score, and dysphagia etiology.

RESULTS

Dysphagia etiology was highly associated with increased development of pulmonary events for some patients, especially those with generalized nonspecific dysphagia due to deconditioning or frailty (hazard ratio [HZ] vs. stroke 2.95, 95% confidence interval [CI]: 1.53-5.69, P = .001) and esophageal dysphagia (HZ: 2.66, 95% CI: 1.17-6.02, P = .019). Dysphagia etiology was also associated with increased mortality for patients with generalized nonspecific dysphagia due to deconditioning or frailty (HZ: 3.32, 95% CI: 2.0-5.52, P < .001), postsurgical patients (HZ: 1.73, 95% CI: 1.05-2.86, P = .032), and chronic neurologic disease (HZ: 1.87, 95% CI: 1.12-3.13, P = .017). Dietary modification recommendations at the time of VFSS (prohibition of oral intake or modification of food consistency) had no significant impact on time to first pulmonary event (P = .37) or survival (P = .17), whereas PAS score was associated with decreased time to first pulmonary event on univariate but not multivariate analysis (HZ for 1-point increase: 1.6, 95% CI: 0.99-1.36, P = .067). Kaplan-Meier estimate of overall 3-year mortality for this patient cohort was 39%.

CONCLUSIONS

Etiology of dysphagia is associated with a higher mortality rate and development of pulmonary events in patients with unsensed penetration or aspiration on VFSS, especially for those patients with generalized deconditioning and frailty or esophageal dysphagia. Severity of aspiration as defined by PAS was not associated with altered overall survival. Recommendations for dietary modification to a nothing by mouth status or modified food consistency had no statistically significant association with development of pulmonary events or survival in patients with detectable unsensed penetration or aspiration on VFSS compared to full-diet recommendation.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:S1-S10, 2017.

Nutritional Aspects of Dysphagia Management

This chapter describes the nutritional aspects of dysphagia management by starting with the definition of these two conditions (dysphagia and malnutrition) that share three main clinical characteristics: (a) their prevalence is very high, (b) they can lead to severe complications, and (c) they are frequently underrecognized and neglected conditions. From an anatomical standpoint, dysphagia can result from oropharyngeal and/or esophageal causes; from a pathophysiological perspective, dysphagia can be caused by organic or structural diseases (either benign or malignant) or diseases causing impaired physiology (mainly motility and/or perception disorders). This chapter gathers up-to-date information on the screening and diagnosis of oropharyngeal dysphagia, the consequences of dysphagia (aspiration pneumonia, malnutrition, and dehydration), and on the nutritional management of dysphagic patients. Concerning this last topic, this chapter reviews the rheological aspects of swallowing and dysphagia (including shear and elongational flows) and its influence on the characteristics of the enteral nutrition for dysphagia management (solid/semisolid foods and thickened liquids; ready-to-use oral nutritional supplements and thickening powders), with special focus on the real characteristics of the bolus after mixing with human saliva.

The Effects of Bolus Volume and Texture on Pharyngeal Pressure Events Using High-resolution Manometry and Its Comparison with Videofluoroscopic Swallowing Study

Background/Aims

The purpose of this study was to develop new parameters of high-resolution manometry (HRM) and to applicate these to quantify the effect of bolus volume and texture on pharyngeal swallowing.

Methods

Ten healthy subjects prospectively swallowed dry, thin fluid 2 mL, thin fluid 5 mL, thin fluid 10 mL, and drinking twice to compare effects of bolus volume. To compare effect of texture, subjects swallowed thin fluid 5 mL, yogurt 5 mL, and bread twice. A 32-sensor HRM catheter and BioVIEW ANALYSIS software were used for data collection and analysis. HRM data were synchronized with kinematic analysis of videofluoroscopic swallowing study (VFSS) using epiglottis tilting.

Results

Linear correlation analysis for volume showed significant correlation for area of velopharynx, duration of velopharynx, pre-upper esophageal sphincter (UES) maximal pressure, minimal UES pressure, UES activity time, and nadir UES duration. In the correlation with texture, all parameters were not significantly different. The contraction of the velopharynx was faster than laryngeal elevation. The durations of UES relaxation was shorter in the kinematic analysis than HRM.

Conclusions

The bolus volume was shown to have significant effect on pharyngeal pressure and timing, but the texture did not show any effect on pharyngeal swallowing. The parameters of HRM were more sensitive than those of kinematic analysis. As the parameters of HRM are based on precise anatomic structure and the kinematic analysis reflects the actions of multiple anatomic structures, HRM and VFSS should be used according to their purposes.

Effect of Bolus Viscosity on the Safety and Efficacy of Swallowing and the Kinematics of the Swallow Response in Patients with Oropharyngeal Dysphagia: White Paper by the European Society for Swallowing Disorders (ESSD)

BACKGROUND

Fluid thickening is a well-established management strategy for oropharyngeal dysphagia (OD). However, the effects of thickening agents on the physiology of impaired swallow responses are not fully understood, and there is no agreement on the degree of bolus thickening.

AIM

To review the literature and to produce a white paper of the European Society for Swallowing Disorders (ESSD) describing the evidence in the literature on the effect that bolus modification has upon the physiology, efficacy and safety of swallowing in adults with OD.

METHODS

A systematic search was performed using the electronic Pubmed and Embase databases. Articles in English available up to July 2015 were considered. The inclusion criteria swallowing studies on adults over 18 years of age; healthy people or patients with oropharyngeal dysphagia; bolus modification; effects of bolus modification on swallow safety (penetration/aspiration) and efficacy; and/or physiology and original articles written in English. The exclusion criteria consisted of oesophageal dysphagia and conference abstracts or presentations. The quality of the selected papers and the level of research evidence were assessed by standard quality assessments.

RESULTS

At the end of the selection process, 33 articles were considered. The quality of all included studies was assessed using systematic, reproducible, and quantitative tools (Kmet and NHMRC) concluding that all the selected articles reached a valid level of evidence. The literature search gathered data from various sources, ranging from double-blind randomised control trials to systematic reviews focused on changes occurring in swallowing physiology caused by thickened fluids. Main results suggest that increasing bolus viscosity (a) results in increased safety of swallowing, (b) also results in increased amounts of oral and/or pharyngeal residue which may result in post-swallow airway invasion, (c) impacts the physiology with increased lingual pressure patterns, no major changes in impaired airway protection mechanisms, and controversial effects on oral and pharyngeal transit time, hyoid displacements, onset of UOS opening and bolus velocity-with several articles suggesting the therapeutic effect of thickeners is also due to intrinsic bolus properties, (d) reduces palatability of thickened fluids and (e) correlates with increased risk of dehydration and decreased quality of life although the severity of dysphagia may be an confounding factor.

CONCLUSIONS

The ESSD concludes that there is evidence for increasing viscosity to reduce the risk of airway invasion and that it is a valid management strategy for OD. However, new thickening agents should be developed to avoid the negative effects of increasing viscosity on residue, palatability, and treatment compliance. New randomised controlled trials should establish the optimal viscosity level for each phenotype of dysphagic patients and descriptors, terminology and viscosity measurements must be standardised. This white paper is the first step towards the development of a clinical guideline on bolus modification for patients with oropharyngeal dysphagia.

Objective prediction of pharyngeal swallow dysfunction in dysphagia through artificial neural network modeling

BACKGROUND

Pharyngeal pressure-flow analysis (PFA) of high resolution impedance-manometry (HRIM) with calculation of the swallow risk index (SRI) can quantify swallow dysfunction predisposing to aspiration. We explored the potential use of artificial neural networks (ANN) to model the relationship between PFA swallow metrics and aspiration and to predict swallow dysfunction.

METHODS

Two hundred consecutive dysphagia patients referred for videofluoroscopy and HRIM were assessed. Presence of aspiration was scored and PFA software derived 13 metrics and the SRI. An ANN was created and optimized over training cycles to achieve optimal classification accuracy for matching inputs (PFA metrics) to output (presence of aspiration on videofluoroscopy). Application of the ANN returned a value between 0.00 and 1.00 reflecting the degree of swallow dysfunction.

KEY RESULTS

Twenty one patients were excluded due to insufficient number of swallows (<4). Of 179, 58 aspirated and 27 had aspiration pneumonia history. The SRI was higher in aspirators (aspiration 24 [9, 41] vs no aspiration 7 [2, 18], p < 0.001) and patients with pneumonia (pneumonia 27 [5, 42] vs no pneumonia 8 [3, 24], p < 0.05). The ANN Predicted Risk was higher in aspirators (aspiration 0.57 [0.38, 0.82] vs no aspiration 0.13 [0.4, 0.25], p < 0.001) and in patients with pneumonia (pneumonia 0.46 [0.18, 0.60] vs no pneumonia 0.18 [0.6, 0.49], p < 0.01). Prognostic value of the ANN was superior to the SRI.

CONCLUSIONS & INFERENCES

In a heterogeneous cohort of dysphagia patients, PFA with ANN modeling offers enhanced detection of clinically significant swallowing dysfunction, probably more accurately reflecting the complex interplay of swallow characteristics that causes aspiration.

Findings of Abnormal Videofluoroscopic Swallowing Study Identified by High-Resolution Manometry Parameters

OBJECTIVE

To identify the parameters of high-resolution manometry (HRM) with a significant correlation to abnormal findings of videofluoroscopic swallowing study (VFSS).

DESIGN

Prospective study.

SETTING

Hospital rehabilitation department.

PARTICIPANTS

Patients with dysphagia symptoms (N=40).

INTERVENTION

Participants were evaluated once using VFSS in neutral head position and evaluated twice using HRM with 5mL of thin fluid.

MAIN OUTCOME MEASURES

HRM parameters included maximal pressure, area integral, rise time, duration of the velopharynx and tongue base, maximal pressure of pre-upper esophageal sphincter (UES), low pharynx, cricopharyngeus, minimal UES pressure, UES activity time, and nadir UES duration. HRM parameters were compared with the findings of VFSS. Receiver operating characteristic analysis was performed to obtain the cutoff value, sensitivity, and specificity of HRM parameters for the prediction of findings of VFSS.

RESULTS

The maximum pressure of the velopharynx showed a significantly positive prediction for most abnormal parameters of VFSS in the pharyngeal phase. Nadir UES pressure duration was significant for impaired laryngeal elevation, residue at pyriformis sinus, and combination of penetration and aspiration. The maximum pressure of the velopharynx <180.0 showed 100% sensitivity and 75% specificity for the presence of penetration and aspiration, and the cutoff point of 178.8 showed 86.7% sensitivity and 75% specificity for the presence of subglottic aspiration.

CONCLUSIONS

This study identified significant HRM parameters that are highly specific for individual abnormalities of VFSS, suggesting the cutoff value, sensitivity, and specificity. Because HRM could inform the quantitative measurement of pharyngeal weakness, the cutoff value for HRM parameters could be used to predict aspiration in patients with pharyngeal weakness.

A hybrid transducer to evaluate stomach emptying by ultrasound and susceptometric measurements: an in vivo feasibility study

Gastric emptying reflects a diversity of important physiological functions. Alternating current biosusceptometry (ACB) is an inexpensive, radiation-free, and minimally invasive method to evaluate gastric emptying, but its response depends on the spatial distribution of the magnetized material and does not provide precise anatomical information. The hybrid transducer, which combines ACB and an ultrasound probe, is an alternative to improve susceptometry measurements, namely the spatial localization of the magnetized source. In this study, initial stomach emptying, in rats, was monitored with the aid of the hybrid transducer. Yogurt mixed with ferrite particles was injected into the rat's stomach. The hybrid transducer was placed on the rat's abdomen during experiments, and the susceptometry signal and magnetomotive ultrasound (MMUS) images were saved and postprocessed. MMUS highlighted the movement of magnetic particles due to magnetic force from ACB excitation coils, and showed the rat's stomach location. In this feasibility study, we monitored the stomach emptying of 4 rats for 20 min. The mean relative ACB signal decayed by 4.6 ± 0.1%, and the mean relative area of MMUS images decreased by 4.5 ± 0.2%, after 20 min postingestion of the magnetic meal due to stomach emptying. In a second experiment, 3-D MMUS images from axial sequences were obtained by spatially translating the hybrid transducer, providing details of the stomach wall, which may enable minimally invasive detection of abnormalities. In conclusion, the MMUS image increased ACB spatial resolution and furnished additional anatomical information.

Adapting human videofluoroscopic swallow study methods to detect and characterize dysphagia in murine disease models

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research. Successful outcomes are dependent upon three critical components: test chambers that permit self-feeding while standing unrestrained in a confined space, recipes that mask the aversive taste/odor of commercially-available oral contrast agents, and a step-by-step test protocol that permits quantification of swallow physiology. Elimination of one or more of these components will have a detrimental impact on the study results. Moreover, the energy level capability of the fluoroscopy system will determine which swallow parameters can be investigated. Most research centers have high energy fluoroscopes designed for use with people and larger animals, which results in exceptionally poor image quality when testing mice and other small rodents. Despite this limitation, we have identified seven VFSS parameters that are consistently quantifiable in mice when using a high energy fluoroscope in combination with the new murine VFSS protocol. We recently obtained a low energy fluoroscopy system with exceptionally high imaging resolution and magnification capabilities that was designed for use with mice and other small rodents. Preliminary work using this new system, in combination with the new murine VFSS protocol, has identified 13 swallow parameters that are consistently quantifiable in mice, which is nearly double the number obtained using conventional (i.e., high energy) fluoroscopes. Identification of additional swallow parameters is expected as we optimize the capabilities of this new system. Results thus far demonstrate the utility of using a low energy fluoroscopy system to detect and quantify subtle changes in swallow physiology that may otherwise be overlooked when using high energy fluoroscopes to investigate murine disease models.

Kinematic and temporal factors associated with penetration-aspiration in swallowing liquids

In this study we undertook careful analysis of 13 quantitative physiological variables related to oropharyngeal swallowing from a sample of 42 subacute patients referred for dysphagia assessment. Each patient underwent a videofluoroscopic swallowing examination in which they swallowed up to five boluses of 22 % w/v ultrathin liquid barium suspension administered by teaspoon. Our goal was to determine whether scores on 13 kinematic or temporal parameters of interest were independently associated with the presence of penetration-aspiration in the final compiled dataset of 178 swallows. Participants were classified as aspirators based on the presence of at least one swallow that demonstrated a Penetration-Aspiration Scale score of ≥3. The parameters of interest included six kinematic parameters for capturing hyoid position, three swallow durations [laryngeal closure duration, hyoid movement duration, and upper esophageal sphincter (UES) opening duration], and four swallow intervals (laryngeal closure to UES opening, bolus dwell time in the pharynx prior to laryngeal closure, stage transition duration, and pharyngeal transit time). Mixed-model repeated-measures ANOVAs were conducted to determine the association between each parameter and aspiration status. Only 1 of the 13 parameters tested distinguished aspirators from nonaspirators: aspirators demonstrated significantly shorter UES opening duration. In addition, a trend toward reduced maximum superior position of the hyoid was seen in aspirators. Limitations and future considerations are discussed.

Dysphagia: implications for older people

Dysphagia represents a salient concern in many conditions prevalent in older people. There are direct implications for morbidity and mortality. The importance of recognizing and managing dysphagia in hospital and the community also extends to psychosocial impact and quality of life, as well as health, economic and ethical-legal issues. This review outlines reasons for the importance of recognizing and treating dysphagia. It then proceeds to look at recent developments in our understanding of the nature, assessment and management of dysphagia in older people. Whilst there are well-established practices in assessment and management, ongoing work continues to challenge the validity and reliability of many methods. These concerns are covered and directions for future developments highlighted.

Physiology of the upper segment, body, and lower segment of the esophagus

The following discussion on the physiology of the esophagus includes commentaries on the function of the muscularis mucosa and submucosa as a mechanical antireflux barrier in the esophagus; the different mechanisms of neurological control in the esophageal striated and smooth muscle; new insights from animal models into the neurotransmitters mediating lower esophageal sphincter (LES) relaxation, peristalsis in the esophageal body (EB), and motility of esophageal smooth muscle; differentiation between in vitro properties of the lower esophageal circular muscle, clasp muscle, and sling fibers; alterations in the relationship between pharyngeal contraction and relaxation of the upper esophageal sphincter (UES) in patients with dysphagia; the mechanical relationships between anterior hyoid movement, the extent of upper esophageal opening, and aspiration; the application of fluoroscopy and manometry with biomechanics to define the stages of UES opening; and nonpharmacological approaches to alter the gastroesophageal junction (GEJ).

Imaging evaluation of dogs and cats with Dysphagia

The current literature is reviewed in this paper regarding the application of diagnostic imaging in the evaluation of swallowing disorders of the dog. The applications of radiography, contrast radiography, and contrast videofluoroscopy are discussed with pertinent case examples provided for emphasis. The indications for image-guided interventions are also described.

Changes of timing variables in swallowing of boluses with different viscosities in patients with dysphagia

OBJECTIVES

To evaluate the timing of the swallowing process and the effect of bolus viscosity on swallowing.

DESIGN

Prospective observational study.

SETTING

General teaching hospital, rehabilitation unit.

PARTICIPANTS

We enrolled patients with dysphagia (n=82) in a videofluoroscopic swallowing study (VFSS) from January 13, 2009, to October 22, 2009. Based on VFSS results, we classified patients as "thin-fluid aspirators" (n=40) or as "nonaspirators" (n=42).

INTERVENTIONS

Swallowing of a 5-mL thick bolus and a 5-mL thin bolus in all patients.

MAIN OUTCOME MEASURES

Kinematic analysis of various variables during the swallowing process (pharyngeal phase), including epiglottis contact with the bolus, laryngeal elevation, pharyngeal constriction, and upper esophageal sphincter opening.

RESULTS

In both groups, the thin bolus arrived at the vallecular pouch earlier than the thick bolus. During swallowing of the thick bolus, the thin-fluid aspirators had a delayed latency of upper esophageal sphincter opening, delayed laryngeal elevation to peak level, and significantly longer rise time of laryngeal elevation.

CONCLUSIONS

Our results indicate clear differences in the degree of adaptation to bolus viscosity between patients classified as thin-fluid aspirators and as nonaspirators. These differences were mainly in activities of laryngeal elevators rather than pharyngeal constrictors.

Does removal of tracheostomy affect dysphagia? A kinematic analysis

Tracheostomy tubes are thought to increase the incidence of aspiration and several mechanisms that might cause this have been suggested. Some studies reported alterations in laryngeal elevation during swallowing, which they attributed to an anchoring effect of the tracheostomy tube resulting in dysphagia. The purpose of the present study was to kinematically investigate the effect of tracheostomy on the swallowing process in dysphagic patients. Thirteen patients (7 males, 6 females; mean age = 61.4 years) were prospectively enrolled between August 2008 and December 2009. The inclusion criteria for a patient who had undergone tracheostomy were an ability to tolerate tube plugging for 48 h and the capacity to expectorate without assistance. All patients underwent two videofluoroscopic swallow studies (VFSS), before and after decannulation. We measured 21 time interval variables during swallowing in the pharyngeal phase and the extent of laryngeal elevation. No patient exhibited any change in swallowing function status [Penetration - Aspiration Scale (PAS) (median value = 1)] in the interval between the two VFSS tests. Upon kinematic analysis, no significant difference in any variable pertaining to laryngeal elevation or pharyngeal constriction was found when pre- and post-decannulation VFSS test data were compared (p > 0.05). The present study thus showed that removal of a tracheostomy tube does not affect the kinematics of swallowing. Our results support previous findings that indicated no relationship between tracheostomy tube placement and dysphagia.